Max, yes, the Wirraway and the Harvard I shared the same wing design. The conversion of the KH Texan kit to a Wirraway requires lots of surgery, but it's the only thing close in 1/32 scale, so it's a useful starting point. My build log is here:
I'm still researching for the other two KH Texan kit builds, so I'll start the build logs for those soon...

I should also have explained that I'm working on 3 of these kits at the moment. Two as Harvards and two as Wirraways.
If that doesn't add up, that's because one of the Harvards is a Wirraway. And that statement will make sense when I put up the build logs on these particular models...

Hi Paulo,
actually, my project is an Australian civilian-operated target towing Mustang, with a second seat and target winch installed behind the pilot. Luckily this conversion used a standard canopy. Here's a link to the (slow) build log:
https://forum.largescaleplanes.com/index.php?/topic/75745-aussie-target-tug-mustang/

Continuing my preparations for this build...
Firstly, I decided that the Hasegawa kit's sparse cockpit details were not going to cut it, since most of the focus for this model is around the cockpit and the modifications for the target towing gear and rear seat. So I sourced a cockpit sprue from the Tamiya P51-D/K Pacific Mustang kit from eBay.
Second, I needed better seats, so I purchased two Barracuda Cast seats. So far I haven't found any photos showing the interior of VH-BOZ in target towing configuration, but these seats will be a good start.
Third, I picked up an excellent set of photos of VH-BOZ from "The Collection" (search for them on eBay), selected by David Muir, author of Southern Cross Mustangs. These are all very useful.
I'm currently working on a 3D CAD model of the Type B towing winch, so that I can get one printed by Shapeways...

I'm enjoying watching this Paolo, as I have to add a rear seat to my Mustang project (although facing rearwards, since the second seat was to operate the target towing winch). Nice work on the two-seat conversion!

Some small progress this evening from aboard my floating workshop...
Here's my "production line" for 1/32 scale Pratt & Whitney R-1340 Wasp engines. I need 2 complete geared engines (one for the Wirraway and one for a Ceres). On the left is the engine from the Kitty Hawk Texan kit, with all the cylinders molded integrally with the crank-case. I'm building this as a test-piece for colours and weathering. On the right are the two resin engines from Vector, with the 3D-printed gear reduction drive housings in front.
P1080572 by Derek Buckmaster, on Flickr
The 3D printed propeller hubs are back from Shapeways, and here is my "production line" for the Hamilton Standard 3D40 propellers:
P1080573 by Derek Buckmaster, on Flickr
The nose of the Wirraway is quite different to the later Texan. I need to remove 9mm from the equipment bay to fit the new "dish-pan" at the rear of the cowl. Here I've marked the section to be removed:
P1080574 by Derek Buckmaster, on Flickr

In addition to getting 3D printed parts from ShapeWays, I'm also experimenting with using my home-made Tevo Tarantula printer to print some parts at home. The Tarantula is a kit which you assemble yourself. I purchased it via a web vendor in China for about A$395.
Being a low-cost printer with only about 0.1mm resolution (layer thickness), I don't expect to be printing complicated parts (I'll save those for SW), but there are still a few less complex parts which should be doable with the Tarantula.
Here you see an almost-finished print of the engine "dish-pan" which covers the engine mount. This is a simple part with features that I'll scribe and glue into place.
IMG_7356 by Derek Buckmaster, on Flickr

Spent some time looking for better blades for the Hamilton Standard prop. The blades in the Kitty Hawk kit are far too thick, so I hunted around for some alternatives to better match the HS 6101A blade as shown in the photo below.
On the left (silver) is the Hamilton Standard prop from a Monogram Grumman Gulfhawk II kit. The shape is better than the Kitty Hawk kit prop, but the diameter is too small. In the middle (bluish grey) is the Kitty Hawk Texan kit prop, too thick and with an oddly tapered root section. On the right (brownish resin) is a Quickboost after-market resin blade from a Mk.Vb Spitfire. This was a Hamilton Standard propeller made under licence by deHavilland, and the blade shape correctly matches the 6101A drawing shape.
HS 6101A blades 2 by Derek Buckmaster, on Flickr

The next part to get the 3D printed treatment is the Hamilton Standard propeller hub.
I decided my attempts to kit-bash the 2-bladed Hamilton Standard 3D40 hub from the Texan kit into a 3-bladed 3D40 hub weren't going to satisfy me. After looking at the possibility of substituting a 3-bladed hub from a couple of different kits in my stash (Williams Brothers Seversky P-35 and Monogram Grumman G-22 Gulfhawk II use the same hub) I still wasn't happy, so I've drawn up the 3D40 hub in TurboCAD and sent the STL file off to Shapeways...
3D40 hub 02 by Derek Buckmaster, on Flickr

The 3D printed reduction drive housings have arrived from Shapeways, and I'm very pleased with the results...
IMG_0311 by
Derek Buckmaster, on Flickr
On the left is an unpainted 3D printed housing, in the middle is a painted version and on the right is the crank-case for a non-geared Pratt & Whitney R-1340 Wasp engine from the Vector resin kit. The ribs and bosses on the 3D printed version look fabulous.
The 3D printed part will now be attached to the front of the resin crank-case, after removing the non-geared front housing detail.
The unpainted 3D printed part on the left also has nuts added (as shown in the 3D model above), but they're not visible in the unpainted state.